This unique semi-detached house is located in the community of Kastanienbaum (“Chestnut Tree”), not far from the City of Lucerne and on the shores of Lake Lucerne. In fact, the property abuts the lake at a woodland area mixed with oak, birch, chestnut and evergreen trees. Imagine the feeling of a stroll in the forest with its atmospheric interplay of light penetrating dense shadows, all leading to a flowering meadow; the goal of retaining this feeling played a major role from the project’s very conception.

The new construction is being located in this picturesque landscape in such a way that only a minimum of the existing terrain is being taken for the actual building. From a concrete deck, a ramp ushers you to the building where a concrete overhang defines the veranda area; from there, a wide stairway leads into the forest. The new exterior space attempts to preserve the existing atmosphere and is covered with a thick grove of birch and cherry trees as well as hedges. The strong presence of the landscape reinforces the perception of living in nature.

A continuous glass facade on the ground floor makes it possible for the inhabitants to enjoy a direct connection with their surroundings. Due to the building’s seemingly floating envelope, it virtually merges into the environment and thereby creates a clearly identifiable dual-purpose space: depending on how the wooden roller shutters are adjusted, the terrace becomes part of the interior or outdoor space. In this way, the open car port is able to become an enclosed garage.

The interrelationship between the interior and exterior is further enhanced by the selection of colours and materials. Black-toned concrete and reddish cherry wood (Jatobá) contrast to nature’s shades of green. In optical terms, the interior spaces with their use of dark materials become inconspicuous, and the surroundings begin to glow depending on how the sunlight strikes them. The mirroring surfaces of the woodwork reflect images of the nearby trees into the interior spaces and further intensify the intimate bond the building has with nature.

The length of the building can be traversed using ramps. These spatial interconnecting elements lead from open living areas to private quarters. The ground floor receives morning sun from the east through the forest, and in the afternoon the sun shines from the west above the hills into the interior courtyard of the upper floor. This serves as a optical extension of the living spaces in the upper floor, and an outdoor stairway connects that floor to the roof level. The ramps invite everyone to experience the building as if “taking a stroll” and give those living there a feeling of openness and spaciousness.

From outside the property, the building does not attract attention at first glance. On the ground floor, strong reflections mirror the surroundings. The wooden roller shutters conceal any movement within the interior spaces. The floating concrete element is skilfully focused towards the insides. Only on the traverse sides are there any slotted openings, but there are no windows. The result is that there’s something mysterious, secretive and sensual about the entire building. The facades do not reveal the insides, so intimate moments remain very private, yet each interior room has a terrace-like outdoor space. Despite the large openings, the threshold to intimacy and security is preserved.

While the rooms in the ground floor are designed to maintain a close relationship to nature, terraces in the upper floor serve as a spatial filter to the surroundings. The openings in the facades offer selected views into the forest, so those living here enjoy a ever changing view depending on the season. The living spaces in the upper floor are alive thanks to the relationship with a rather introverted inner courtyard. On the sides, circular openings create a play of light in the courtyard, and the round perforations in the concrete allow you to experience the material’s thickness and dark colourations.

The roof terrace, on the other hand, adds a completely different element to the quality of life and is equally accessible to both parties as a value added feature. In the summer, it can serve as additional living space with a generous view onto the lake and the mountains. The connection to the nearby lake is perceptible with all your senses. At night, the building and the black pool seem to dissolve within the darkness, and taking a swim under the stars becomes a special experience.

The rooms are kept dark but are accentuated in spots with artificial light. The natural way light streams through the large front windows is gently softened by the absorption on the dark walls and ceilings, resulting in a subdued atmosphere of lighting. Bright, very colourful rooms are stimulating, while darker rooms project a mood that encourages retreat, peace and quiet. In these rooms, busy professionals can counteract their hyperactive workday by “slowing down the pace”.

In these twin houses, only three types of material are used. First, the black-toned structural concrete is exposed at the walls and ceilings, while the terrace floors are made up of joint-free solid concrete. Next, the gleaming reddish and very hard cherry wood from Brazil (Jatobá) is used for all interior floors, the wooden railing on the roof terrace and the underside layers of the terraces as seen from the ground floor. Because this wood is of such high quality, this material can even be used as the shower floor in the bathroom. Finally, these first two materials are enhanced with built-in, gleaming anthracite-coloured woodwork.

Thanks to the reflections it throws off, the kitchen and cabinets seem to dissolve into thin air. This composition of materials alone creates a comfortable mood and unique atmosphere in this space. The materials “vibrate” in tune with each other and take on an incredible glow.

The structure making up the architecture, its shape, logical construction and functionality have all been developed specifically for this location and to enhance the lives of those living there. The harmonious interplay gives the building its identity. It has been created for specifically for this site and would not make sense anywhere else. Timeless architecture reaching beyond any momentary trends or unnecessary gimmicky shapes and forms – these are the aspirations we had in mind when conceiving the Kastanienbaum Twin houses.